Keratoconus 1

Keratoconus, the most common corneal dystrophy, is a bilateral, noninflammatory progressive corneal ectasia. Clinically, the cornea becomes progressively thin and conical, resulting in myopia, irregular astigmatism, and corneal scarring. The disease usually arises in the teenage years, eventually stabilizing in the third and fourth decades. The incidence of keratoconus is 1 in 2,000 in the general population; it occurs with no ethnic or gender preponderance, and causes significant visual impairment in young adults. No specific treatment exists except to replace the corneal tissue by surgery (corneal transplantation) when visual acuity can no longer be corrected by contact lenses (summary by Dash et al., 2006). Ihalainen (1986) reviewed various conditions with which keratoconus is at times associated. Keratoconus is frequent in cases of amaurosis congenita of Leber (204000). Genetic Heterogeneity of Keratoconus Also see KTCN2 (608932), mapped to 16q22.3-q23.1; KTCN3 (608586), mapped to 3p14-q13; KTCN4 (609271), mapped to 2p24; KTCN5 (614622), mapped to 5q14.1-q21.3; KTCN6 (614623), mapped to 9q34; KTCN7 (614629), mapped to 13q32; KTCN8 (614628), mapped to 14q24; and KTCN9 (617928), caused by mutation in the TUBA3D gene (617878) on 2q21. [from OMIM]